To express 10 to the power of 2, you simply write it as 102. This notation means that you multiply 10 by itself, which can also be written as 10 × 10. When you calculate this, you get 100.
In mathematical terms, the exponent (in this case, 2) tells you how many times to use the base number (which is 10) in a multiplication. So, 102 = 10 × 10 = 100.