Tag Archives: number

What number am I? – Prime numbers and perfect squares

Math Teaser I am a perfect square. My square root is a prime number, less than 100, and the digits of the square root add up to a perfect square. My own digits add up to a prime number. [doptoggle title=”Click Here to see the Solution!!!” icon=5 activeicon=6] To solve this, we need to first determine what the options for […]

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What are Prime Numbers? Is 2 a prime number?

prime number, prime numbers, 4th grade maths

Prime numbers are any numbers that cannot be evenly divided by any integer other than 1 and itself. Or in other words, the only numbers that you can multiply to get a prime number are 1 and the prime number. Numbers that are not prime, or those with additional factors other than 1 and itself, are called composite numbers. The […]

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What is a gigabyte? Computer hardware numbers

computer hardware, binary numbers, computer math, coolmath

1 point 21 Gigabytes!?! What the heck is a gigabyte? Read on for a quick explanation of computer hardware units – bytes and hertz.        Computer Hardware: Information storage and memory Memory and storage sizes are usually a total of the number of bytes of data that can be retained.  A byte is a single piece of data, like a […]

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A Sequence

Math Teaser! If the first five terms of a sequence are 0, 2, 8, 18, 32 what would be the value of the tenth term? [doptoggle title=”Click Here to see the Solution!!!” icon=5 activeicon=6] Start by looking at how each term in the sequence is related to the others. Since the terms grow bigger and bigger by an increasing margin […]

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What Number am I? – Square, cube, prime digits

Math Teaser I am a 3 digit number whose product of my digits is equal to 144. Of my 3 digits, one is a cube, one is a square, and one is a prime. If the six numbers that meet these criteria are listed in increasing order, I am fifth in the list. [doptoggle title=”Click Here to see the Solution!!!” […]

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What Number am I? – Combination of digits

Math Teaser I am 3 digits. My digits add up to 10. The product of my digits is 20. I am an odd number. The digit in the hundreds place plus the digit in the tens place equals the digit in the ones place. The smallest digit is in the middle. [doptoggle title=”Click Here to see the Solution!!!” icon=5 activeicon=6] […]

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One million – how big is a million, really?

one million, 1 million, million, how big is a million, mathematics, coolmath

1,000,000 is huge! Maybe it seems common because we hear it so much, but look at the examples below to get a better understanding of the huge-ness of 1 million. You may never think the same about a million again. Examples of one million How long is 1 million seconds? 1 million seconds / (3600 seconds/hour x 24 hours/day) = […]

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The 11’s trick

A cool math trick to help you multiply many (but not all…) two digit numbers by 11 – very quickly and in your head! Let’s start with a simple example:   11 * 12 = 132 Do you notice anything about the product? (The “product” is what the answer of a multiplication problem is called) See how the answer 132 has […]

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Roman Numerals – Practice Worksheet

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Try your skill at reading Roman Numerals. Roman Numeral Worksheet Roman Numeral Practice (download the pdf) Fold the bottom of the sheet under so you don’t look at the answers while you figure out the Numerals. If you need a reminder on how they work, check out the Roman Numerals explained page! Don’t miss our other math worksheets for other […]

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Roman Numerals – symbols and counting

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Roman Numerals are all around us – sometimes hiding in plain sight. Maybe you have a few basics memorized and you don’t even notice them. Or maybe, you have no idea what they are… Either way, here is a quick look at how they work and the math behind them, then you can jump over to the Practice Page for […]

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I always have a calculator, I don’t need to learn this…

Sure, you have a nice phone – So what! Even cheapie phones have a calculator built in. And so what if you always have it with you. If you are practiced in your math skills, you can still make an estimated calculation faster in your head than you can do it by digging your phone out and navigating to the […]

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multiples of 3 – an answer check and factoring trick

So here is a neat math trick to help make some sense of how numbers combine when dealing with 3 and its multiples (3,6,9,12…).  This falls in the “cool, but wierd, but oddly useful” bucket. Check your multiplication answers Any time you multiply by 3, the digits in the answer will always add up to a multiple of 3.  For […]

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Some squares and cubes you should know

What is a square? When a number is multiplied by itself, the result is called the square of that number. For example, 3 * 3 = 9.  This is the same as saying 3 squared, or written with an exponent as 32, and 9 is called the square of 3. This type of calculation is used frequently in math.  Many formulas […]

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A crazy way to get to 8

This is a fun little math game , see if you can follow the calculations- 1: Think of any number – this is Your Number. 2: Subtract 1 from Your Number. 3: Multiply the answer by 3. 4: Add 12 to the answer. 5: Divide the answer by 3. 6: Add 5 to the answer. 7: Subtract Your Number from the […]

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Multiplying by 9’s

Did you know that when you multiply a 9 by another single digit that the digits of the product will add up to 9? This an easy way to help you remember the multiples of 9 and is helpful in checking your answer.   Let’s take a look: Notice that the 1 and the 8 in the 18 add up […]

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