571 + 175 = 746 472 + 274 = 746 373 + 373 = 746 076 + 670 = 746
What is the number if it divides exactly by 13 and when you write its digits in reverse order you make a square number. (You get a square number when you multiply a number by itself - 64 is square because it is 8 times 8)
How many ways can you find to make the number 10, by adding or subtracting prime numbers? The same numbers but in a different order count as the same answer. (Prime numbers are only divisible by themselves and 1 so they are 2, 3, 5, 7, 11, 13, ...)
When a two digit number is multiplied by sum of its digits, the product is 715 but when the reverse of a two digit number is multiplied by sum of its digits the product obtained is 99 less. What is the sum of the digits of a number?
