Subtract Within 1,000 to Re-route Starlight Station's Power (Grade 3)

The power line is scrambled and re-routing it means three-digit subtraction: 705 − 208, 640 − 175, the kind with a zero in the middle that makes borrowing awkward. The number line carries jumps of a hundred as well as one, so a cadet can move in place-value-sized steps instead of crawling. That is the strategy the standard is actually describing — breaking the number apart rather than following a procedure — and the controls make it the fastest route.

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What this station asks for

🛰️ Re-route the PowerThe power line is scrambled. Solve each subtraction and slide your rocket to the exact number on the big number line to re-route the flow. Use the +/-100 jumps for the big hops! You work out the answer, then slide the rocket along a number line to set the course. Five tasks, then a snack wrapper goes into the Case File.

Five questions it might ask

Drawn from the same pool the activity uses, so these are the real thing rather than an illustration. The numbers change on every attempt — there is no fixed set to memorize.

Question	Answer
550 − 271 = ?	279
884 − 75 = ?	809
937 − 94 = ?	843
862 − 195 = ?	667
449 − 263 = ?	186

👀 What to watch for

Numbers with a zero in the tens column are where third grade subtraction breaks. If 705 − 208 comes back as 507, the digits were subtracted in whichever direction was easier. The hundred-jumps on the number line make that answer look visibly wrong, which is half the repair.

The Common Core standard behind it

Official wording, quoted in full — not our summary of it:

3.NBT.A.2	Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.

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Other Grade 3 skills in this case

Multiples3.OA.C.7 Multiplication word problems3.OA.C.7 Skip counting3.OA.C.7

All grades

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