How do you do Common Core multiplication?

Question

You break down the numbers in the problem to smaller numbers

49 x 59 =

40 x 50 = 2000

40 x 9 = 360

50 x 9 = 450

9 x 9 = 81

Total 2891

Answer 1

49 * 59 =

(40 + 9)(50 + 9) =

40*50 + 40*9 + 50*9 + 9*9 <--- FOIL method

2000 + 360 + 450 + 81

2000 + 300 + 60 + 400 + 50 + 80 + 1

2000 + 700 + 190 + 1 =

2891

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Here's 3 by 3

123 * 987

(100 + 20 + 3) ( 900 + 80 + 7) =

100 *900 + 100*80 + 100*7 +

20 *900 + 20*80 + 20*7 +

3 * 900 + 3*80 + 3*7 =

90000 + 8000 + 700

18000 + 1600 + 140 +

2700 + 240 + 21

'adds the diagonals

=

90000 + 26000 + 5000+ 380 + 21

116000 + 5000 + 380 + 21 =

121401