1 / 21 + 1 / 77 + 1 / 165. + 1 / 3245 simple calculation, please answer before 22 o'clock,

1 / 21 + 1 / 77 + 1 / 165. + 1 / 3245 simple calculation, please answer before 22 o'clock,

1/21+1/77+1/165.+1/3245 =1/3*7+1/7*11+1/11*15.+1/55*59=1/4(1/3-1/7)+1/4(1/7-1/11)+1/4(1/11-1/15)+.1/4(1/55-1/59)=1/4(1/3-1/7+1/7-1/11.-1/59)=1/4(1/3-1/59)=1/4X56/177=14/177

The length of 77 is 101 minus 77. 404 times 25 is my simple calculation, 38 times 58 plus 38 times 43 minus 38
77 long 101 minus 77 simple calculation
404 times 25 is a simple calculation,
Simple calculation process of 38 times 58 plus 38 times 43 minus 38

77X100+77-77

How to calculate 782 * 101-782

782×101-782
=782×(101-1)
=782×100
=78200
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4.25 △ 2.5 × 101-1.7 simple calculation

=1.7×（100+1）-1.7
=1.7×100+1.7-1.7
=170