Grandmother's age from the digits

MediumBrainteasers~5m

A grandmother has two grandchildren whose ages happen to be the two digits of the grandmother's (two-digit) age. The three ages sum to 9898. How old is the grandmother?

Show hints (2)+
  1. Grandmother's age =10d1+d2=10d_1+d_2; grandchildren are d1d_1 and d2d_2. Form the sum equation.
  2. 11d1+2d2=9811d_1+2d_2=98 with digit constraints forces d1=8,d2=5d_1=8,d_2=5.

Answer

Reveal answer →

85

Want the full step-by-step worked solution? It's part of Premium - along with a worked solution for every question in the bank.

Asked at: Jane Street, SIG

Related questions