what is the least whole number that should be added to 784839 if it is to be divisible by 10 ?
"a number is divisible by 10 if the last digit is 0 . here , 784839 = 9 , ( last digit is not 0 . 1 must be added to 784839 to make it divisible by 10 c"
subtract(add(subtract(784839, const_1), 10), 784839)