Question

Three digit numbers ,in which the middle digit is a perfect square, are formed using the digits 0 to 9. Their sum is

• A. 194220
• B. 270540
• C. 170055
• D. none of these

Answer 1

The correct option is A 194220

Perfect square digits $:0,1,4,9$

Number of times they occur $=4\times 10\times 9=360$

Sum of unit digits $=36(0+1+2+...+9)=1620$

Sum of tenth digits $=90(0+1+4+9)=1260$

Sum of hundredth digits $=40(1+2+....+9)=1800$

$\therefore$ Sum of all required 3 digit numbers $=1800\times 100+1260\times 10+1620=194220$