KA-0145Grid coordinates and lattice reasoning
3 points, difficulty 1 of 3Level 5–6about 45sA counter sits at the point (3, 5) on a grid. It moves 4 squares right and 2 squares down. Where is it now?
Hints
Take them one at a time. The first gives nothing away.
1A nudge
Across changes the first number, up changes the second.
2The strategy
The first coordinate is how far across and the second is how far up. Right adds to the first, down subtracts from the second. Change them one at a time.
3The full solution
Moving 4 right takes 3 to 7. Moving 2 down takes 5 to 3. So the counter is at (7, 3).
Solution— no shortcut on this one
The first number says how far across, the second how far up. Moving 4 squares right adds 4 to the first: 3 + 4 = 7. Moving 2 squares down subtracts 2 from the second: 5 - 2 = 3. So the counter is at (7, 3). The transferable idea: change one coordinate at a time and say the direction out loud - right adds, left subtracts, up adds, down subtracts.
Why this is on the test: Swapping the coordinates or the sign of a direction accounts for almost every lost mark on grid questions.