How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

I am an odd number. Take away a letter and I become even. What number am I?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?

What does this mathematical rebus means ?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

There is a number which when you multiply by 3 and subtract 2 from the result, then the resulting number is the reverse of the actual number.

What is the smallest number that stands true on the statement?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *