Grade 8 Adding Numbers in Scientific Notation
Adding in scientific notation for grade 8: match the powers of ten first, then combine the coefficients. Sixteen problems with a full answer key.
Add. Give both numbers the same power of 10 first, then write the answer in scientific notation.
- 1.(2.7 x 10^4) + (7.5 x 10^4) =
- 2.(6.8 x 10^5) + (4.8 x 10^4) =
- 3.(3.2 x 10^2) + (5.2 x 10^3) =
- 4.(5.7 x 10^6) + (5.3 x 10^7) =
- 5.(7.5 x 10^9) + (4.2 x 10^9) =
- 6.(5.6 x 10^5) + (2.2 x 10^4) =
- 7.(1.1 x 10^6) + (9.6 x 10^6) =
- 8.(3.5 x 10^9) + (2.4 x 10^9) =
- 9.(7.9 x 10^8) + (7.8 x 10^9) =
- 10.(4.7 x 10^8) + (8.9 x 10^9) =
- 11.(5.4 x 10^8) + (6.5 x 10^7) =
- 12.(3.1 x 10^5) + (1.9 x 10^6) =
- 13.(7.2 x 10^4) + (2.0 x 10^4) =
- 14.(3.5 x 10^3) + (5.8 x 10^3) =
- 15.(8.8 x 10^2) + (5.7 x 10^3) =
- 16.(5.9 x 10^7) + (7.0 x 10^6) =
What this worksheet covers
Sixteen addition problems fill the page, and the complete key sits behind them in the same PDF. The expressions carry exponents, including the zero and negative cases that break the "repeated multiplication" reading; the operands are decimals rather than whole numbers. It is written against Common Core 8.EE.4 — part of Expressions & Equations in grade 8.
Skills practiced
The skill underneath these problems is signed rational numbers and scientific notation. Working the page asks a student to keep decimal points aligned rather than right-aligning digits out of habit; apply exponent properties instead of expanding every term. Consistency across the page matters more than any single answer on it.
How to use this worksheet
Have the student estimate before computing, then compare. At this level an answer that is wildly off should announce itself, and building that reflex matters as much as the sixteen answers themselves. Date the sheet before filing it. A page from six weeks ago is the cheapest evidence you have that something is sticking.
One mistake to watch for
Decimals aligned to the right: 3.5 + 0.42 = 3.92.
The right-alignment habit from whole-number addition is being applied to a notation where position, not the right edge, determines value.
Have the student write in the missing placeholder zero (3.50) before adding. Aligning the decimal points then aligns everything else automatically.
Related worksheets
Also aligned to 8.EE.4
The same standard from a different angle. Worth reaching for when the skill needs another pass without repeating the identical page.
- Grade 8 Multiplying Numbers in Scientific Notation — grade 8, 16 problems
- Grade 8 Subtracting Numbers in Scientific Notation — grade 8, 16 problems
A step either side
Addition either side of grade 8, for stepping the difficulty rather than repeating it.
- Grade 7 Adding Rational Numbers — grade 7, 20 problems
Free to download, free to print, and free to photocopy for a whole class — this addition sheet and its key are one PDF, aimed at signed rational numbers and scientific notation.