Several arithmetic problems (Grade 6) a.6/11*17-12*3/11 b.（1+1/2）*（1-1/2）*（1+1/3）*（1-1/3）*...*（1+1/9）*（1-1/9） c.1/27+505/2727+131313/272727+101010/272727 d. Known: 1 / 2-1 / 3 = 1 / 2 * 3, calculated: 1 / 2 * 3 + 1 / 3 * 4 + 1 / 4 * 5 + 1 / 5 * 6 +... + 1 / 19 * 20 Note: (/) stands for fractional line. For example: 505 / 2727 = 2727, numerator 505, (*) stands for multiplication 1 / 2-1 / 3 = 1 / 2 * 3, which means 1 / 2-1 / 3 = 1 / 2 * 3

Several arithmetic problems (Grade 6) a.6/11*17-12*3/11 b.（1+1/2）*（1-1/2）*（1+1/3）*（1-1/3）*...*（1+1/9）*（1-1/9） c.1/27+505/2727+131313/272727+101010/272727 d. Known: 1 / 2-1 / 3 = 1 / 2 * 3, calculated: 1 / 2 * 3 + 1 / 3 * 4 + 1 / 4 * 5 + 1 / 5 * 6 +... + 1 / 19 * 20 Note: (/) stands for fractional line. For example: 505 / 2727 = 2727, numerator 505, (*) stands for multiplication 1 / 2-1 / 3 = 1 / 2 * 3, which means 1 / 2-1 / 3 = 1 / 2 * 3

a. The original formula = (6 * 17-12 * 3) / 11 = (17-2 * 3) * 6 / 11 = 11 * 6 / 11 = 6B. The original formula = 3 / 2 * 1 / 2 * 4 / 3 * 2 / 3 *... * 10 / 9 * 8 / 9 = (3 / 2 * 4 / 3 * 5 / 4 *... * 10 / 9) * (1 / 2 * 2 / 3 * 3 / 4 *... * 8 / 9) = (10 / 2) * (1 / 9) = 5 / 9C. The original formula = 1 / 27 + (101 * 5) / (101 * 27) + (10101 * 13) / (10101 * 27) + (10101 *