Math Olympiad for 3rd Grade – 4

Posted on October 1, 2021 by kevin
  1. Kevin was calculating the product of two numbers. One of the numbers is 78. However, instead of using 78, he was using 87 and the result was off by 45. The other number used in multiplication is __________.
  2. The sum of two 3-digit numbers, $abc$ and $def$, is 1995. Then the sum of all 6 digits $a+b+c+d+e+f$ is __________.
  3. The difference of two 3-digit numbers, $abc$ and $def$, is 892. Then the products of all digits of two numbers, $a\times b\times c\times c\times d\times e\times f$ is __________.
  4. Comparing $345\times 347$ to $346 \times 346$, which one is bigger? __________.
  5. The sum of several natural numbers is $11$. The maximum possible value of multiple them together is __________.
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Math Olympiad for 3rd Grade – 3

Posted on September 24, 2021 by kevin
  1. Black stones and white stones are arranged on the table in the following pattern: 
    ⚫◯◯⚫⚫⚫◯⚫⚫◯◯◯⚫◯◯⚫⚫⚫◯⚫⚫◯◯◯⚫◯◯⚫⚫⚫ ......
    The color of the 999th stone is __________ and there are ____________ white stones among the 999 stones.
  2. For the following sequence of numbers: $$1, 4, 7, 10, 13, 16, 19, 22, 25, …….$$ The $2020^{th}$ number in the above sequence is ________.
  3. For the following sequence of numbers: $$1, 2, 4, 7, 11, 16, 22, 29, ……$$ where the first number is $1$, the second number is one more than the first, the third number is one more than the second, and so on. The remainder of the $2020^{th}$ number divided by 5 is __________.
  4. Chaining the following sequence numbers together $$1, 2, 3, 4, …… 97, 98, 99, 100, 101$$ to form a very big number $$123456……979899100101$$ There are __________ digits in the above big number.
  5. The product of $10000$ natural numbers is $10000$. The maximum sum of those $10000$ numbers is __________.

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Math Olympiad for 3rd Grade – 2

Posted on September 17, 2021 by kevin
  1. The total number of 2-digit positive integers with the ten-digit greater than the unit-digit is __________.
  2. The sum of 20 consecutive natural numbers is 2010. The smallest one is __________ and the largest one is __________.
  3. The following are rows of equations: $$4+2=6$$ $$5+8=13$$ $$6+14=20$$ $$7+20=27$$$$……$$ The equation of the 99th row is __________.
  4. To cut a pizza into 11 pieces, the minimum number of straight cut required with a knife is __________.
  5. You are required to subtract 285 from 3000, add 282 to it; then subtract 285 and add 282 again; repeat the process until the number become 0. The number of subtractions performed is __________.
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Math Olympiad for 3rd Grade – 1

Posted on September 10, 2021 by kevin
  1. Use symbol $+$, $-$, $\times$ and $\div$ to fill in the blanks to make the following equation: $$ \texttt{1}\ \boxed{　}\ \texttt{2}\ \boxed{　}\ \texttt{3}\ \boxed{　}\ \texttt{4}\ \boxed{　}\ \texttt{5}\ =\ \texttt{20}$$
  2. Find the value of the following: $$9999999+999999+99999+9999+999+99+9$$
  3. Find the value of the following: $$1+2-3+4-5+6-7+8-9+…+2018-2019+2020$$
  4. Find the value of the following: $$1+2+3-4-5+6+7-8-9+…+2018+2019-2020$$
  5. $a$,$b$,$c$,and $d$ are different single digit numbers and $$ \begin{array} \ \ \ \ \ \ \ \ \texttt{ a b c d}\\ \ \ \ \dfrac{\times　　　\texttt{　　　9}}{　\texttt{ d c b a }}\end{array}$$ The value of 4-digit number $abcd$ is __________.
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Fun Math Puzzles – 1

Posted on August 17, 2021 by kevin

My calculator is broken, it only has two working buttons. One of them adds $1$ to the result and the other doubles it. What is the minimum number of presses needed to get to 2021?

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