Question

Which of the following will have 9 as its unit digit?

• A. ${14}^2$
• B. ${15}^2$
• C. ${17}^2$
• D. ${19}^2$

Answer 1

The correct option is C ${17}^2$

${17}^2=289$
The number which has either 3 or 7 in its unit digit will have 9 in the unit digit of its square.