An MRI gradient is a checked position-to-frequency address rule. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A gradient makes field a position address
Start with base field 1 tesla and gradient 1 tesla per metre.
B(x)=Bbase+Gx
Frequency follows the checked field
With gamma 4 hertz per tesla, the three fields 1, 2, 3 tesla give 4, 8, 12 hertz.