Because 259 is close to 260, 259 times 89 is about 260 times 80. Is that right or wrong?
3 and 4 are close to 5, 3 times 4 and 5 times 5, the difference is very big = = if 260 is such a big number, how big is the error
3 and 4 are close to 5, 3 times 4 and 5 times 5, the difference is very big = = if 260 is such a big number, how big is the error