Question

how many significant figures are in 2.90870 MHz?

Answer 1

here's a hint:

1.Non-zero digits are significant
2. Zeros between non-zero digits are significant
3. Zeros not in between non-zero digits are not significant

does that help?

Answer 2

another hint: nearly all of them are significant.

Answer 3

ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant.

Answer 4

oh yes. that too