Printable primary math worksheet for math grades 1 to 6 based on ... - Free Printable

Let's solve each sequence step by step and identify the pattern in each.

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1. 183, 203, ____, ____, ____, 283, 303

- Difference between 183 and 203:
$ 203 - 183 = 20 $
- So, the pattern is +20 each time.
- Let’s fill in:
- 203 + 20 = 223
- 223 + 20 = 243
- 243 + 20 = 263
- Then: 263 + 20 = 283 ✔
- 283 + 20 = 303 ✔

✔ Sequence: 183, 203, 223, 243, 263, 283, 303
✔ Pattern: Add 20

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2. ____, ____, 277, 287, 297, 307, 317

- Look at known numbers: 277, 287, 297, 307, 317 → increasing by 10 each time.
- So, go backward:
- 277 - 10 = 267
- 267 - 10 = 257

✔ Sequence: 257, 267, 277, 287, 297, 307, 317
✔ Pattern: Add 10

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3. 145, 160, ____, ____, ____, 220, 235

- 160 - 145 = 15 → so likely +15 each time.
- Check: 220 to 235 = +15 ✔
- Fill in:
- 160 + 15 = 175
- 175 + 15 = 190
- 190 + 15 = 205
- 205 + 15 = 220 ✔

✔ Sequence: 145, 160, 175, 190, 205, 220, 235
✔ Pattern: Add 15

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4. ____, ____, 307, 332, 357, 382, 407

- 332 - 307 = 25
- 357 - 332 = 25
- So pattern: +25
- Backward:
- 307 - 25 = 282
- 282 - 25 = 257

✔ Sequence: 257, 282, 307, 332, 357, 382, 407
✔ Pattern: Add 25

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5. 181, 221, ____, ____, ____, 381, 421

- 221 - 181 = 40 → possibly +40
- Check: 381 to 421 = +40 ✔
- So add 40 each time:
- 221 + 40 = 261
- 261 + 40 = 301
- 301 + 40 = 341
- 341 + 40 = 381 ✔

✔ Sequence: 181, 221, 261, 301, 341, 381, 421
✔ Pattern: Add 40

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6. ____, ____, 280, 295, 310, 325, 340

- 295 - 280 = 15
- 310 - 295 = 15 → so +15
- Backward:
- 280 - 15 = 265
- 265 - 15 = 250

✔ Sequence: 250, 265, 280, 295, 310, 325, 340
✔ Pattern: Add 15

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7. 222, 242, ____, ____, ____, 322, 342

- 242 - 222 = 20 → likely +20
- 322 - 342 = -20? Wait — 342 - 322 = 20 ✔
- So add 20:
- 242 + 20 = 262
- 262 + 20 = 282
- 282 + 20 = 302
- 302 + 20 = 322 ✔

✔ Sequence: 222, 242, 262, 282, 302, 322, 342
✔ Pattern: Add 20

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8. ____, ____, 312, 342, 372, 402, 432

- 342 - 312 = 30
- 372 - 342 = 30 → so +30
- Backward:
- 312 - 30 = 282
- 282 - 30 = 252

✔ Sequence: 252, 282, 312, 342, 372, 402, 432
✔ Pattern: Add 30

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9. 123, 173, ____, ____, ____, 373, 423

- 173 - 123 = 50 → likely +50
- 373 to 423 = +50 ✔
- Add 50:
- 173 + 50 = 223
- 223 + 50 = 273
- 273 + 50 = 323
- 323 + 50 = 373 ✔

✔ Sequence: 123, 173, 223, 273, 323, 373, 423
✔ Pattern: Add 50

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10. ____, ____, 400, 475, 550, 625, 700

- 475 - 400 = 75
- 550 - 475 = 75 → so +75
- Backward:
- 400 - 75 = 325
- 325 - 75 = 250

✔ Sequence: 250, 325, 400, 475, 550, 625, 700
✔ Pattern: Add 75

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11. 180, 240, ____, ____, ____, 480, 540

- 240 - 180 = 60 → likely +60
- 480 to 540 = +60 ✔
- Add 60:
- 240 + 60 = 300
- 300 + 60 = 360
- 360 + 60 = 420
- 420 + 60 = 480 ✔

✔ Sequence: 180, 240, 300, 360, 420, 480, 540
✔ Pattern: Add 60

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12. ____, ____, 265, 320, 375, 430, 485

- 320 - 265 = 55
- 375 - 320 = 55 → so +55
- Backward:
- 265 - 55 = 210
- 210 - 55 = 155

✔ Sequence: 155, 210, 265, 320, 375, 430, 485
✔ Pattern: Add 55

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✔ Final Answers:

| Sequence | Missing Numbers | Pattern |
|--------|------------------|---------|
| 1. 183, 203, __, __, __, 283, 303 | 223, 243, 263 | Add 20 |
| 2. __, __, 277, 287, 297, 307, 317 | 257, 267 | Add 10 |
| 3. 145, 160, __, __, __, 220, 235 | 175, 190, 205 | Add 15 |
| 4. __, __, 307, 332, 357, 382, 407 | 257, 282 | Add 25 |
| 5. 181, 221, __, __, __, 381, 421 | 261, 301, 341 | Add 40 |
| 6. __, __, 280, 295, 310, 325, 340 | 250, 265 | Add 15 |
| 7. 222, 242, __, __, __, 322, 342 | 262, 282, 302 | Add 20 |
| 8. __, __, 312, 342, 372, 402, 432 | 252, 282 | Add 30 |
| 9. 123, 173, __, __, __, 373, 423 | 223, 273, 323 | Add 50 |
| 10. __, __, 400, 475, 550, 625, 700 | 250, 325 | Add 75 |
| 11. 180, 240, __, __, __, 480, 540 | 300, 360, 420 | Add 60 |
| 12. __, __, 265, 320, 375, 430, 485 | 155, 210 | Add 55 |

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✔ Summary of Patterns:

All sequences follow an arithmetic pattern (constant difference between terms). The key was to:
1. Find the difference between two known consecutive terms.
2. Verify that this difference holds throughout.
3. Use it to fill in missing numbers forward or backward.

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