AMC 10 · 2019 · #1

Grade 6 arithmetic
exponentsorder-of-operationsidentify-subproblems identify-subproblemspattern-recognition ↑ Prerequisites: exponentsorder-of-operations
📏 Short solution 💡 2 insights
Problem
Compute 2^{(0^(1⁹))} + ((2⁰)¹)⁹ — a stacked tower of exponents on the left and a chain of exponents on the right.

Pick an answer.

(A)
0
(B)
1
(C)
2
(D)
3
(E)
4

AMC 10 2019 problem © Mathematical Association of America (MAA AMC). Reproduced for educational use.

How to solve
Strategy Identify Subproblems

Tool #7 (Subproblems): the expression is a sum of two pieces — solve each piece separately and add. Inside each piece, evaluate exponents innermost-first, one tiny step at a time. Tool #5 (Pattern): the recurring facts 1^anything = 1 and 2⁰ = 1 do almost all the work. Tool #3 (Eliminate): once we notice each piece is 1, the sum can only be 2, ruling out (A), (B), (D), (E).

1STEP 1

Split into two pieces: L = 2^{(0^(1⁹))} and R = ((2⁰)¹)⁹, solve each, then add.

L + R where L = 2^{(0^(1⁹))}, R = ((2⁰)¹)⁹
2STEP 2

Innermost first: 1⁹ = 1, then 0¹ = 0, then 2⁰ = 1, so L = 1.

1⁹ = 1 → 0¹ = 0 → 2⁰ = 1, so L = 1
3STEP 3

Same way: 2⁰ = 1, then 1¹ = 1, then 1⁹ = 1, so R = 1.

2⁰ = 1 → 1¹ = 1 → 1⁹ = 1, so R = 1
4STEP 4

Add the pieces: L + R = 1 + 1 = 2, which is choice (C).

L + R = 1 + 1 = 2 → (C)
5STEP 5

Elimination check: two pieces each equal to 1 can only sum to 2, so (C).

L = 1, R = 1 → 2 = (C)
Answer
2
Both pieces of the expression simplified independently to 1, and 1 + 1 = 2. The choices (A) 0, (B) 1, (D) 3, (E) 4 are impossible because two non-zero parts each equal to 1 must sum to exactly 2. (C) 2 is consistent.
💡Key takeaway

This AMC 10 problem only needs Grade 6 "evaluate expressions with whole-number exponents" you already know — every 1 to a power stays 1, every 2⁰ is 1, so each piece is 1 and the sum is 2.