TF32 = FP32 range + FP16 precision
The effective mantissa is like FP16 but it's padded out to be the same size as FP32.
In other words, there's 1 sign bit, 8 exponent bits, 10 mantissa bits that are USED, and 13 mantissa bits that are IGNORED.
1 + 8 + 10 + 13 = 32
The 13 ignored mantissa bits are part of the memory image: they pad the number out to 32-bit alignment.