AMC 10 · 2022 · #1

Grade 6 arithmetic
absolute-valueorder-of-operationsfunction-evaluation identify-subproblems ↑ Prerequisites: order-of-operationsabsolute-value
📏 Short solution 💡 1 insight
Problem
A new symbol is defined: applying it to two numbers gives the absolute difference between them. The parentheses tell which pair to combine first. Find the difference between the results of the two ways of grouping.

Pick an answer.

(A)
${-}2$
(B)
${-}1$
(C)
0
(D)
1
(E)
2
How to solve
Strategy Identify Subproblems

The expression has two separate halves joined by a minus sign, and each half has an inner ◆ that must be done first. Tool #7 (Subproblems) says: compute the left half on its own, compute the right half on its own, then subtract. The order-of-operations rule plus the absolute-value definition do all the work — no algebra needed. Tool #3 (Eliminate) is the multiple-choice safety net: once we have a numerical value, we read off the matching letter.

1STEP 1

Inside the left grouping

Start inside the parentheses.

2 ◆ 3 = |2 - 3| = 1
2STEP 2

Finish the left grouping

The left side comes out zero.

1 ◆ 1 = |1 - 1| = 0
3STEP 3

Inside the right grouping

Start inside on the right too.

1 ◆ 2 = |1 - 2| = 1
4STEP 4

Finish the right grouping

The right side gives a different value.

1 ◆ 3 = |1 - 3| = 2
5STEP 5

Subtract the two

Subtracting gives negative two.

0 - 2 = -2 → (A)
Answer
-2
Sanity check the two halves. Left half closes with 1 ◆ 1, and any number ◆ itself is 0 — that's the smallest possible value. Right half closes with 1 ◆ 3, two numbers that sit 2 apart, so the value is 2. A small number minus a bigger number gives a negative result, so 0 - 2 = -2 has the right sign and size to match choice (A).
💡Key takeaway

This AMC 12 problem only needs Grade 6 "absolute value is just the distance between two numbers" — once you read the parentheses carefully, the two halves come out to 0 and 2, and the difference is -2.