how come when I do a sum in my head i get a different answer to the calculator - the sum is 7+7/7+7*7-7.
That's because ur calculator knows the order of operations : *,\ always before +,- so 7 + 7/7 + 7*7 - 7 becomes 7 + (7/7) + (7*7) - 7 = 50
