How to compute 143 + 305*70 using a calculator or mental math tricks?
Executive summary
Compute 143 + 305×70 by doing the multiplication first: 305×70 = 21,350, then add 143 to get 21,493 (calculation steps and mental tricks below). Online basic calculators (e.g., Calculatorsoup) will do both multiplication and addition in one entry if you prefer a device [1].
1. Multiply first, add second — the correct order of operations
Standard arithmetic rules say do multiplication before addition, so 305×70 must be computed before adding 143; calculators and mental methods follow that order automatically (available sources describe basic calculators that handle multiplication and addition operations) [1].
2. Straight calculation with a basic calculator — fastest and error‑free
Use any simple online or handheld calculator (web sites like Calculatorsoup or calculator.net offer basic calculators) to enter 305×70 then +143; the device evaluates 305×70 = 21,350 and then adds 143 to return 21,493 [1] [2].
3. A one‑line calculator entry you can type now
If you type the whole expression 143+30570 into a scientific or online calculator that follows standard operator precedence, it will compute 30570 first and return 21,493. Symbolic solvers can also simplify such expressions step by step (symbolab offers step‑by‑step simplification tools) [3].
4. Mental math: break the multiplication into friendlier chunks
A reliable mental route is to split 305×70 into (300×70) + (5×70). Compute 300×70 = 21,000 and 5×70 = 350, then add to get 21,350; finally add 143 to reach 21,493. This method uses the distributive property and is the same principle shown in multiplication‑trick materials that recommend splitting numbers into tens/hundreds plus units [4] [5].
5. Mental math alternative: use tens first and adjust
Another quick method: compute 305×7 = 2,135 (multiplying by 7 is smaller mentally), then append a zero for ×70 → 21,350; add 143 → 21,493. Multiplying by a single digit then shifting by a zero is a standard trick endorsed across multiplication tips resources [6] [7].
6. Check your arithmetic with complementary addition tricks
When adding 21,350 + 143, pair round numbers to simplify: 21,350 + 150 = 21,500, then subtract 7 (because 143 is 7 less than 150) → 21,493. Addition tricks like rounding to a convenient tens value and compensating are common in fast‑calculation guides [8] [9].
7. Why these approaches are reliable — and their limits
Calculator use guarantees correctness as long as you trust input and operator precedence; basic online calculators cited explicitly perform these operations [1] [2]. Mental splitting relies on knowing multiplication tables and simple addition/subtraction; multiplication‑trick guides recommend exactly these decompositions but note individual preference and fluency affect speed [4] [5].
8. When step‑by‑step solvers help learning, not just answers
If you want a worked solution for practice, math steps engines (e.g., Symbolab) show the same decomposition in detail so you can learn the method rather than only seeing the final number [3]. Such tools are useful for students learning the distributive property and place‑value tricks.
9. Final numeric answer and quick recap
Following order of operations: 305×70 = 21,350; then 21,350 + 143 = 21,493. If you prefer a device, use any basic online calculator (Calculatorsoup, calculator.net) or a step‑solver for an explained solution [1] [2] [3].
Limitations and sourcing note: This piece uses general calculator and mental‑math resources provided in the supplied search results; available sources do not mention alternative numeric outcomes or contest the arithmetic above.