Multiplication. (a×10m)(b×10n)=(ab)×10m+n.
Worked example. (3×104)×(4×105)=12×109=1.2×1010.
(Note: 12×109 is NOT yet in standard form — 12 is not between 1 and 10. Adjust: 12=1.2×101, so 12×109=1.2×1010.)
Division. b×10na×10m=ba×10m−n.
Worked example. 2×1038×107=4×104.
Worked example. 6×1073×104=0.5×10−3=5×10−4.
(Again, adjust to bring a into 1≤a<10.)
Addition / subtraction. Convert to the SAME power of 10 first.
Worked example. (2.5×105)+(3×104).
- Rewrite second: 3×104=0.3×105.
- Add: (2.5+0.3)×105=2.8×105.
This is the most error-prone step — students often forget to align the powers and just add the a values directly.