Reasoning · Grade 3-1 Three-Digit Calculation
Problem
1, 2, 3 keeps all six arrangements: 12 × 111 = 1332.
Listing all six orders carefully guarantees I count every number once; the place-value grouping confirms the total.
2.NBT.A.1Make A Systematic List2, 3, 3 repeats down to three: 233 + 323 + 332 = 888.
Because two cards match, I list only the distinct numbers so I do not add the same number twice.
2.NBT.A.1Make A Systematic List0, 4, 7 drops the two leading zeros: 407 + 470 + 704 + 740 = 2321.
A leading 0 would make a two-digit number, so those arrangements simply do not count as three-digit numbers.
2.NBT.A.1Make A Systematic ListAny arrangement that puts 0 at the front is not a three-digit number at all, so those orders are simply dropped.
The leading digit is the count of hundreds, and a count of zero hundreds means the numeral only reaches the tens place.
Once the leading-zero orders are struck out, what is left is exactly the arrangements the problem is asking about.
List every arrangement neatly, toss out the ones starting with 0, and you will never miss or double-count a number!