6.28 * 3.7 + 62.8 * 0.63 = 5 / 7 + 1 / 3 * 9 + 4 / 13=

6.28 * 3.7 + 62.8 * 0.63 = 5 / 7 + 1 / 3 * 9 + 4 / 13=

Original formula = 6.28 * 3.7 + 6.28 * 10 * 0.63 = 6.28 (3.7 * 10 * 0.63) = 6.28 * 10 = 62.8
Original formula = 5 / 7 + 3 + 4 / 13 = 3 + 45 / 91 + 28 / 91 = 3 and 73 / 91

（1+1/2）×（1+1/3）×（1+1/4）×…… A simple algorithm for × (1 + 1 / 8) × (1 + 1 / 9) × (1 + 1 / 10)

3*4*5…… *11/2*3*4…… *10=11/2
For example, 1 + 1 / 2 = 3 / 2
1+1/3=4/3
……
1+1/10=11/10
It can be seen that the dislocation of numerator and denominator can be offset, and the last digit of numerator and the first digit of denominator can be retained, that is, the result 11 / 2, without any other simple algorithm

How to calculate 2 + 4 + 8 + 10 + 96+98+100

Sum formula with arithmetic sequence (first term + last term) * number of terms / 2
（2+100）*50/2
=2550
Number of items = (last first) / tolerance + 1
Note: tolerance is the difference between two adjacent items