when the number get too big like, 12^17 mod 12 .. it just didn't show up

currently using CASIO fx-570MS scientific calculator

doing RSA and Diffie Helman cryptography tutorial.. i wonder how to calculate the modulus in scientific calculator

Use human brain.

12 to the power of any integer (1 or above) modulus 12 is always zero. Because modulus is the remainder, and if all the factors in the number is 12, then modulus 12 would always be zero.

Scientific calculators do not have arbitrary precision. For other large values, to check the remainder, use an arbitrary precision calculator like bc (comes free with Linux. There might be a windows port somewhere if you look hard enough).

for example

thanks for the explanation dkk