Multiple choice

Find the largest positive integer that will divide 398, 436 and 542 leaving remainders 7, 11 and 15 respectively?

  1. 12

  2. 13

  3. 15

  4. 17

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Subtract remainders from numbers: 398-7=391, 436-11=425, 542-15=527. Find HCF(391,425,527). 391=17×23, 425=17×25, 527=17×31. HCF = 17. Verify: 398÷17=23 rem7, 436÷17=25 rem11, 542÷17=31 rem15. Correct.