You may have already learned different forms in which a number can be written. "Expanded form" is a form in which the digits are summed according to their place value:

35 = 30 + 5, for example, or

459 = 400 + 50 + 9

The "make a ten" strategy for addition or subtraction makes use of this different form of number representation. Also, it makes use of some additional facts, based on subtraction, rather than addition.

9 = 10 - 1

8 = 10 - 2

7 = 10 - 3

and so on.

Generally, the strategy is to represent a number in terms of a convenient multiple of 10, then perform the addition and/or subtraction.

Example 1

34 + 23 = (30 + 4) + (20 + 3)

= (30 + 20) + (4 + 3)

= 50 + 7 = 57

Example 2

34 + 28 = (30 + 4) + (30 - 2)

= (30 + 30) + (4 - 2)

= 60 + 2 = 62

Example 3

34 - 28 = (30 + 4) - (30 - 2)

= (30 - 30) + 4 -(-2)

= 4+2 = 6

The break apart strategy is similar, except you are not constrained to choose multiples of 10.

Example 4

34 - 28 = (38 - 4) - 28

= 10 - 4 = 6

Here is another discussion of break apart strategy.

35 = 30 + 5, for example, or

459 = 400 + 50 + 9

The "make a ten" strategy for addition or subtraction makes use of this different form of number representation. Also, it makes use of some additional facts, based on subtraction, rather than addition.

9 = 10 - 1

8 = 10 - 2

7 = 10 - 3

and so on.

Generally, the strategy is to represent a number in terms of a convenient multiple of 10, then perform the addition and/or subtraction.

Example 1

34 + 23 = (30 + 4) + (20 + 3)

= (30 + 20) + (4 + 3)

= 50 + 7 = 57

Example 2

34 + 28 = (30 + 4) + (30 - 2)

= (30 + 30) + (4 - 2)

= 60 + 2 = 62

Example 3

34 - 28 = (30 + 4) - (30 - 2)

= (30 - 30) + 4 -(-2)

= 4+2 = 6

The break apart strategy is similar, except you are not constrained to choose multiples of 10.

Example 4

34 - 28 = (38 - 4) - 28

= 10 - 4 = 6

Here is another discussion of break apart strategy.