Find the largest

It is given that on dividing 70 by the required number, there is a remainder 5. This means that 70 − 5 = 65 is exactly divisible by the required number. Similarly, 125 − 8 = 117 is also exactly divisible by the required number.

65 =5 × 13

117 = 3² × 13

⇒ Required number = 13 HCF = 13