MEDIUM
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IMPORTANT
Earn 100

Let Fx denote the sum of the digits of the positive integer x. For example, F8=8 and F123=1+2+3=6. For how many two-digit values of x is FFx=3 ?

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Important Questions on Number System

EASY
IOQM - PRMO and RMO
IMPORTANT
Given that 38·52=ab, where both a and b are positive integers, find the smallest possible value for a+b+9325.
EASY
IOQM - PRMO and RMO
IMPORTANT
What is the largest integer that is a divisor of n+1n+3n+5n+7n+9 for all positive even integers n?
MEDIUM
IOQM - PRMO and RMO
IMPORTANT
The product of three consecutive positive integers is 8 times their sum. What is the sum of their squares?
EASY
IOQM - PRMO and RMO
IMPORTANT
Let Pn and Sn denote the product and the sum, respectively, of the digits of the integer n. For example, P23=6 and S23=5. Suppose N is a two-digit number such that N=PN+SN. What is the units' digit of N?
MEDIUM
IOQM - PRMO and RMO
IMPORTANT
The mean of three numbers is 10 more than the least of the numbers and 15 less than the greatest. The median of the three numbers is 5 . What is their sum?
EASY
IOQM - PRMO and RMO
IMPORTANT
Two non-zero real numbers, a and b, satisfy ab=a-b. Then find the possible value of ab+ba-ab?
HARD
IOQM - PRMO and RMO
IMPORTANT
There are N number of positive integers not exceeding 2001 are multiples of 3 or 4 but not 5. Then find the value of N-150
EASY
IOQM - PRMO and RMO
IMPORTANT

In the magic square shown, the sums of the numbers in each row, column, and diagonal are the same. Five of these numbers are represented by v, w, x, y, and z. Find y+z

v 24 w
18 x y
25 z 21