How to calculate 1 * 15 2 * 14 3 * 13 4 * 12 5 * 11 6 * 10 7 * 9 8 * 8

How to calculate 1 * 15 2 * 14 3 * 13 4 * 12 5 * 11 6 * 10 7 * 9 8 * 8

1*15=（8-7）*（8+7)=8^2-7^2=64-49=15
2*14=(8-6)*(8+6)=8^2-6^2=64-36=28
.
7*9=(8-1)*(8+1)=8^2-1^2=64-1=63
8*8=8^2=64
A ^ B means a to the power of B

Simple calculation of 25 × [4 × 12] × 7

=（25x4)X(12X7) =100X84 =8400

Using recursive equation to calculate (those that can be easily calculated should be easily calculated) 35,4-12.5 △ 25 + 1.7

35,4-12.5÷25+1.7
=35+4/10-1(2+1/2)/25+17/10
=35+4/10-25/2/25+17/10
=35+4/10-5/10+17/10
=35+16/10
=36.6

Simple operation of 14 / 25 × 12 + 7 / 25 × 14 + 42 / 25 × 2

14/25×12+7/25×14+42/25×2
＝12×14/25+7×14/25+6×14/25
＝(12+7+6)×14/25
＝25×14/25
＝14