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break the seven into to numbers (3 and 4 because 3+4=7) Mulitply both of these numbers by 3 3x3=9 4x3=12 Then add together the products of the two numbers 12+9=21 example for 8x5: 4+4=8 4x5=20 4x5=20 20+20=40 Hope this helps

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16y ago

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