How to calculate 65.7 × (7.884 △ 657)?

How to calculate 65.7 × (7.884 △ 657)?

65.7 △ 657 × 7.884 simple

Simple calculation of 657657 * 494-494494 * 657

657657×494－494494×657
＝657×1001×494－494×1001×657
＝0

Fast calculation: 3456 × 353656 × 1434535 × 6457567 × 501573455 × 657 × 576 × 676 × 6767 × 777 × 56 × 6745 × 657 × 67568

1.28085012877396 * 10 ^ 59 (mental)

Simple calculation of 99 × 99 + 199

=99*(100-1)+(100+99）
=99*100-99+100+99
=99*100+100
=（99+1）*100
=100*100
=10000

Simple calculation of 19999 + 1999 + 199 + 99 + 4

99+199+1999+19999+4
=(100-1)+(200-1)+(2000-1)+(20000-1)+(1+1+1+1)
=(100+200)+(2000+20000)+(1-1)+(1-1)+(1-1)+(1-1)
=300+22000+0+0+0+0=22300

A simple algorithm of 101 divided by 101 and 101 out of 102

101/(101+101/102)
=101/[101*(1+1/102)]
=1/(1+1/102)
=1/(103/102)
=102/103

99 / 101 × 102

99 of 101 × 102 = (102-1) × 99 / 102 = 102 × 99 / 102-1 × 99 / 102 = 99-99 / 102 = 98 and 1 of 34

(2 + 4 + 6 + 8 + 10 +. + 100 + 102) - (1 + 3 + 5 + 7 +. + 99 + 101) simple algorithm

（2+4+6+8+10+.+100+102）-（1+3+5+7+.+99+101）
=(2-1)+(4-3)+(6-5)+…… +（102-101）
=1+1+1+…… +1 (51 in total, 1 102 / 2 = 51)
=51

Calculation by simple algorithm: 1997 ^ 3-1998 × 1999 × 2000

1997^3－1998×1999×2000
=1997^3-1999(1999^2-1)
=1999-[1999^3-1997^3]
=1999-2[1999^2+1999*1997+1997^2]
=1999-2[(1999-1997)^2+3(1998+1)(1998-1)]
=1999-2[4+3(1998^2-1)]
=1999-6*1998^2-2
=2000-6*(2000-2)^2-3
=2000-24000000+48000-24-3
=23950027

99 / 98 times 97, simple algorithm

=(98-1)x99/98
=99-99/98
=97+1/98
=97 and 1 / 98