Q&A for How to Speed Up Numeric Calculations in Mathematics

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  • Question
    How do you find 175*102?
    Community Answer
    First multiply 175 by 100: that's 17,500. Now multiply 175 by 2: that's 350. Finally, add those two results together: 17,500 + 350 = 17,850.
  • Question
    How do we find the square of 68?
    I_l1ke_gam3s
    Community Answer
    Multiply 68 by 68.
  • Question
    How do you multiply a number less than 100 by a number more than 100? For example, 98×106.
    I_l1ke_gam3s
    Community Answer
    Multiply 98 by 100 to get 9800. Then multiply 98 by 6. You get 588. Finally, add 9800 to 588 to get the final answer of 10,388.
  • Question
    How do I show my work for how much is 259g at $8.60 /kg?
    Joy
    Community Answer
    Divide the number of grams by 1,000 to convert to kilograms, and then multiply by the price per kilogram.
  • Question
    How do we find the square of 68?
    Community Answer
    We multiply 68 by itself: (68)(68) = 4624.
  • Question
    How do you make successors?
    Joy
    Community Answer
    To "make successors" means to identify, develop, and prepare certain employees within an organization to take over critical roles when current leaders leave. You do this through mentorship, training, and gradually increasing responsibilities, ensuring a smooth transition within the company. This process is called "succession planning."
  • Question
    How do you multiply 306 by 402 quickly?
    Community Answer
    Those two zeroes help make it easy. 6 x 2 = 12. 6 x 4 = 24. So the first partial product is 2412. The second partial product is 0. The third partial product is 1206, because 3 x2 = 06, and 3 x 4 = 12. Line up the partial products correctly, and the final product is 123,012.
  • Question
    The trick with 9: 49/9 = 4 (by your trick), but it is actually 5 with a remainder of 4.
    Community Answer
    That "trick" (Step 7) works most of the time, but not when the second digit of the dividend (the numerator) is 9. The article neglects to mention that. (There are other problems with that "trick," too.)
  • Question
    How do you quickly multiply 306 by 402?
    Community Answer
    Those zeroes make it fairly easy. Let's make 306 the top multiplier and 402 the bottom. Get the first partial product by multiplying 306 by 2 (you can probably do that in your head): it's 612. The second partial product is zero, and you can ignore that. The third partial product is found by multiplying 306 by 4 (again, in your head): that's 1224. Place the 4 in that partial product below the 6 in the first partial product (so that there's nothing placed above the 122). Finally, add the properly aligned partial products to get the final product: 23,012.
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