SASMO 2021 Grade 4 Question 1

Platform: start at 0; Q1–15 are worth 2 each, Q16–25 worth 4 each; wrong/blank 0; maximum 70. Official SASMO reference: initial 15, Section A +2/−1/0 (correct/wrong/blank), Section B +4/0/0; maximum 85.

Calculate $654+546+465-456-564-645$.