Explain how you can solve 40 and 16 by breaking apart the numbers

40 x 16

double the first and 1/2 the second

80 x 8

double the first and 1/2 the second

160 x 4

double the first and 1/2 the second

320 x 2

double the first and 1/2 the second

640 x 1 = 640.

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If you meant something like (40) * (10+5+1)

then distribute the 40 to get

400 + 200 + 40

which equals 640.