Calculation: one and a quarter - 9 / 20 + 11 / 30-13 / 42 + 15 / 56-17 / 72 + 19 / 90

Calculation: one and a quarter - 9 / 20 + 11 / 30-13 / 42 + 15 / 56-17 / 72 + 19 / 90


One and a quarter - 9 / 20 + 11 / 30-13 / 42 + 15 / 56-17 / 72 + 19 / 90 = (1 + 1 / 4) - (1 / 4 + 1 / / 5) + (1 / 5 + 1 / 6) - (1 / 6 + 1 / 7) + (1 / 7 + 1 / 8) - (1 / 8 + 1 / 9) + (1 / 9 + 1 / 10) = 1 + 1 / 4-1 / 4-1 / 1 / / 5 + 1 / 5 + 1 / 6-1 / 7 + 1 / 7 + 1 / 8-1 / 9 + 1 / 10 = 1 + 1 / 1 / 10 = 11 / 1