Mission: rewrite the expression so it is easier to calculate
- Inspect the two products and identify the common factor they truly share.
- Watch the signs: a negative sign may be hidden in the other factor. For example, 28×(−15) and (−28)×15 have the same product.
- Make a prediction first. Later levels include subtraction, so the sign between the two terms must be preserved when factoring.
- Normal mode has 12 levels, starts at 100 points, and deducts 5 points for each valid wrong attempt. Retry the same question.
Score：100
Time：00:00
Which equivalent expression is best for a quick distributive-law calculation?
Observe first; do not expand everything. Find the common factor, then check whether the two terms are joined by + or −.
① Rewrite both products with the same common factor.
② Use the distributive law backward and factor out the common factor.
③ Calculate inside the parentheses, then multiply once.
💡 What this level is really teaching
Do not judge only by appearance. Use multiplication sign rules and the commutative property to rewrite both products with the same common factor, then apply the distributive law backward.