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an x am, where n + m = 10

A strategy to multiply any two two-digit-numbers that have the __same first digit (tens) __ and __their second digits (units) add up to 10__.

38 x 32 = 1216

How we got 1216

Step 1: Multiply «

3 x (

Step 2: Multiply the last two digits to get the second part of our answer.

8 x 2 = 16

17 x 13 = 221

How we got 221

Step 1: Multiply «

1 x (

Step 2: Multiply the last two digits to get the second part of our answer.

7 x 3 = 21

25 x 25 = 625

How we got 625

Step 1: Multiply «

2 x (

Step 2: Multiply the last two digits to get the second part of our answer.

5 x 5 = 25

62 x 68 = 4216

How we got 4216

Step 1: Multiply «

6 x (

Step 2: Multiply the last two digits to get the second part of our answer.

2 x 8 = 16

96 x 94 = 9024

How we got 9024

Step 1: Multiply «

9 x (

Step 2: Multiply the last two digits to get the second part of our answer.

6 x 4 = 24

41 x 49 = 2009

How we got 2009

Step 1: Multiply «

4 x (

Step 2: Multiply the last two digits to get the second part of our answer.

1 x 9 = 09

Note that we add an extra zero if the product is less than 10. Here the answer is 2009 and not 209.

39 x 31 = 1209

How we got 1209

Step 1: Multiply «

3 x (

Step 2: Multiply the last two digits to get the second part of our answer.

9 x 1 = 09

Note that we add an extra zero if the product is less than 10. Here the answer is 1209 and not 129.