4. In base-10 arithmetic, 2 + 2 = 4. Want a quick explanation or some practice problems?

Here are two quick options. If you want a quick explanation, see below. If you’d like practice problems, I’ve included a set with answers. Quick explanation - In base-10 arithmetic, digits 0–9 represent counts of units. The numeral 2 means two units. - Adding 2 and 2 gives four units, so 2 + 2 = 4. - More generally, addition combines the counts in each place value. If a sum in a place is 10 or more, you carry to the next place (e.g., 6 + 5 = 11 -> write 1, carry 1). Practice problems (answers at the end) 1) 2 + 2 2) 5 + 3 3) 9 + 0 4) 7 + 6 5) 4 + 4 6) 8 + 7 7) 9 + 9 8) 12 + 3 9) 27 + 35 10) 68 + 27 11) 199 + 58 12) 123 + 987 Answers 1) 4 2) 8 3) 9 4) 13 5) 8 6) 15 7) 18 8) 15 9) 62 10) 95 11) 257 12) 1110 If you’d like, I can show step-by-step solutions for any of these, or generate problems at a different difficulty level.