# Addition and subtraction in different bases a relationship

### Number Systems and Bases – BetterExplained

standing and procedural understanding of addition and subtraction. Building on connections and relationships among these and other mathematical topics. subtraction, such as the number line, a hundreds chart, and base- ten place- value. They invent a procedure that mirrors the actions or relationships described in the . Additional types of multiplication and division problems are introduced later in the .. are available to focus students' attention on the base structure of the. understanding numbers, ways of representing numbers, relationships among numbers, and There are many ways to add, subtract, multiply, or divide numbers. •• It is important to . CCSS: Number & Operations in Base Ten: nickchinlund.info, nickchinlund.info

Most likely because we have 10 fingers. Imagine numbers as ticking slowly upward — at what point do you flip over the next unit and start from nothing? Enter zero And what happens when we reach ten? Suffice it to say, Zero is one of the great inventions of all time.

Look how unwieldly their numbers are without it. Considering other bases Remember that we chose to roll over our odometer every ten. Our counting looks like this: Everything OK so far, right?

Note that we use the colon: In base 10, each digit can stand on its own. Try Base 16 If we want base 16, we could do something similar: We could use some squiggly lines or other shapes, but the convenions is to use letters, Roman style. Just like 5 became V, programmers use letters A-F to get enough digits up to Intervention studies with U.

Their subtraction accuracy became as high as that for addition. These experiences help students see how addition and subtraction are related and help them recognize when to add and when to subtract.

### Numbers in Different Bases | The Oxford Math Center

For students in grades K to 2, learning to see the part-whole relations in addition and subtraction situations is one of their most important accomplishments in arithmetic. Examining the relationships between addition and subtraction and seeing subtraction as involving a known and an unknown addend are examples of adaptive reasoning. By providing experiences for young students to develop adaptive reasoning in addition and subtraction situations, teachers are also anticipating algebra as students begin to appreciate the inverse relationships between the two operations.

They learn skip-count lists for different multipliers e. They then count on and count down these lists using their fingers to keep track of different products. They invent thinking strategies in which they derive related products from products they know. As with addition and subtraction, children invent many of the procedures they use for multiplication. They find patterns and use skip counting e. Finding and using patterns and other thinking strategies greatly simplifies the task of learning multiplication tables see Box 6—4 for some examples.

Commutativity reduces that number by about half. Multiplication by 0 and by 1 may quickly be deduced from the meaning of multiplication. Single-digit multiplication by 9 is simplified by a pattern: Multiplication by 5 may also be deduced through patterns or by first multiplying by 10 and then dividing by 2, since 5 is half of The remaining 15 multiplication combinations and their commutative counterparts may be computed by skip counting or by building on known combinations.

Note that these strategies require proficiency with addition. To compute multiples of 6, one can build on the multiples of 5. If students are comfortable with such strategies for multiplication by 3, 4, and 6, only three multiplication combinations remain: These can be derived from known combinations in many creative ways. Thus, treating multiplication learning as pattern finding both simplifies the task and uses a core mathematical idea.

## Number Systems and Bases

After children identify patterns, they still need much experience to produce skip-count lists and individual products rapidly. Little is known about how children acquire this fluency or what experiences might be of most help. A good deal of research remains to be done, in the United States and in other countries, to understand more about this process.

Single-Digit Division Division arises from the two splitting situations described above. A collection is split into groups of a specified size or into a specified number of groups. Just as subtraction can be thought of using a part-part-whole relation, division can be thought of as splitting a number into two factors.

Hence, divisions can also be approached as finding a missing factor in multiplication. This practice can occur in many different contexts, including solving word problems. Explaining how procedures work and examining their benefits, as part of instruction, support retention and yield higher levels of performance.

Practicing single-digit calculations is essential for developing fluency with them. It is helpful for some practice to be targeted at recent learning. After students discuss a new procedure, they can benefit from practicing it. For example, if they have just discussed the make-a procedure see Box 6—2solving problems involving 8 or 9 in which the procedure can easily be used provides beneficial practice. It also is helpful for some practice to be cumulative, occurring well after initial learning and reviewing the more advanced procedures that have been learned.

This scattershot form of practice is, in our opinion, rarely the best use of practice time. Early in learning it can be discouraging for students who have learned only primitive, inefficient procedures. This list is first used as a counting tool; then it becomes a representational tool in which the number words themselves are the objects that are counted.

During this progression, individual children use a range of different procedures on different problems and even on the same problem encountered at different times. They are just slower than others in moving through it. Single-digit subtraction is usually more difficult than addition for U. If children understand the relationship between addition and subtraction, perhaps by thinking of the problem in terms of part-part-whole, then they recognize that counting up can be used to solve subtraction problems.

### Adding and subtracting 3 fractions (video) | Khan Academy

This recognition makes subtraction more accessible. Multiplication and division are somewhat more difficult.

Learning these combinations seems to require much specific pattern-based knowledge that needs to be orchestrated into accessible and rapid-enough products and quotients. Research into ways to support such pattern finding, along with the necessary follow-up thinking and practice, is needed if all U.

Acquiring proficiency with single-digit computations involves much more than rote memorization. This domain of number demonstrates how the different strands of proficiency contribute to each other. Children begin with conceptual understanding of number and the meanings of the operations. Instead they split the answer into two digits, record the right hand digit in the same column and carry the left hand digit into the column over one place left.

Suppose the sum in a column was 16 An answer of 16 is two digits.

**Adding numbers of a base different than 10**

Subtract 16 - 10 to get 6. Record the 6 in the same column. Record the 1 as a carry in the next column to the left. Procedure to Add Two Base-n Numbers 1.

## Section 4 Binary Logic

If one number is shorter extend it by adding leading zeros to the front of the number. The digits may be A,B,C etc and if so, mentally convert them to decimal before adding. Remember to record a carry digit as explained below - even if it is zero. Keep the decimal sum in your head - or write it down on some scratch paper. Compare the sum in your head with the radix n. A sum less than n is just recorded at the bottom of the same column.

Be careful to write the sum as a single base-n digit. Write a 0 as the carry in the next column left. A sum greater or equal to n requires several steps: Subtract in decimal in your head the radix n from the sum of the digits you already computed.