Add and subtract decimals (6th grade math lesson)
Here we practice adding and subtracting decimals with up to 6 decimal places (digits). The principle is easy: add the numbers place-by-place, just like whole numbers (based on place value, in other words). I give several examples of doing that with mental math. Then we also solve a few algebraic problems (evaluate expressions & solve equations) that involve adding or subtracting decimals.
See also
Math Mammoth Fractions & Decimals 3 — self-teaching worktext
Multiplying decimals by decimals: the shortcut — video lesson