OPCODES Multiplication problem type(uint).max * 2

Question

I try to execute the following opcodes and computer gives me the following result

the code: type(uint).max * 2

the result: type(uint).max -1

PUSH1 2

PUSH32 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF


MUL

Could you explain this result?

Answer 1

The EVM has 256 bits operations, so the result of any operations that do not fit within the 256 will be truncate.

In this case the result should be:

0x1fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe

When truncated to 256 it results in

0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe