Question

Solve each multiplication problem

Using any method. Then she has to use rounding and estimation to check work give me an example for this problems I have no idea how to help my daughter ..... 45x61??? 83x27 ? 63x 87? 15x92? 33x43? 69x63?

Answer 1

Explanation:

For multiplying 2 digit numbers, I like to multiply the ones place and the tens place separately, then add the result.

For example:

45 × 61

45 × 60 + 45 × 1

For the first product, we can repeat the process:

40 × 60 + 5 × 60 + 45 × 1

2400 + 300 + 45

2745

To check our answer, we can round 45 up to 50, and 61 down to 60.

50 × 60 = 3000

This is close to our answer of 2745, so that makes sense.

Let's try another:

83 × 27

83 × 20 + 83 × 7

80 × 20 + 3 × 20 + 80 × 7 + 3 × 7

1600 + 60 + 560 + 21

2241

Using rounded numbers:

80 × 30 = 2400

Let's do one more:

63 × 87

63 × 80 + 63 × 7

60 × 80 + 3 × 80 + 60 × 7 + 3 × 7

4800 + 240 + 420 + 21

5481

Using rounded numbers:

60 × 90 = 5400