Everyone has their own talents. Obviously, I’m a writer. Math, on the other hand, has never been my speciality. I knew from early on that not even the greatest calculator on the planet could get me to either enjoy or be great at math. And that’s OK, because I’m well past my grade-school years and am doing just fine without remembering how to divide fractions!

But for those of you who liked math back in school and want to take a walk down memory lane, check out these so-called “grade-school level” math problems that have recently stumped the internet (as well as these poor children’s parents!).

Good luck!

## 1. Fill In The Missing Numbers.

The puzzle below, comprised of five numbers and four empty circles waiting to be filled in, comes with no further instructions than “Study the number pattern” and “Fill in the missing numbers.” Can you crack it?

https://twitter.com/matigary/status/864872952675872768

**Answer**: One possible answer: 2, 2, 1, 1 (clockwise).

**Explanation**: The figure in the middle circle (three) equals the number of double-digit numbers in the surrounding quadrants (18, 10, 12).

## 2. Fill In The Gaps With Digits From 1 To 9

For this one, you need to fill in the gaps with digits from one to nine so that the equation makes sense following the order of operations: multiply first, then divide, add and, finally, subtract.

**Answer**: Eventually, it turns out (by order of the blank spaces) that a = 3, b = 2, c = 1, d = 5, e = 4, f = 7, g = 9, h = 8 and i = 6.

**Explanation**: Rewrite the snake as an equation:

a + (13b/c) + d + 12e – f – 11 + (gh/i)– 10 = 66

We are trying to find a, b, c, d, e, f, g, h and i, which we know are some combination of the digits 1, 2, 3, 4, 5, 6, 7, 8 and 9. Simplify the equation to:

a + (13b/c) + d + 12e – f +(gh/i) = 66 + 11 + 10 = 87

or

a + d – f + (13b/c) + 12e +(gh/i) = 87

The complete solution can be found here.

According to the VN Express, this was a problem for third graders in the town of Bao Loc, Vietnam. Eight-year-olds figured it out!

## 3. How Many Marbles?

This problem goes like this:

- Grace has
**10**fewer marbles than Paul. - Grace has
**5**more marbles than Meghan. - Paul gives
**4**marbles to Meghan. - Grace gives another
**6**marbles to Meghan. - Meghan now has
**13**marbles.

How many marbles did everyone **start out** with?

**Answer**: Meghan had 3 marbles, Grace had 8 marbles, and Paul had 18 marbles.

**Explanation**: The trick here is starting with the number you *definitely* know. In this case, it’s that Meghan has 13 marbles. The rest of the information is all “more than” or “less than” statements, but no actual numbers. So, if we start with the 13 and work backwards, the rest falls into place. Before she had 13 marbles, Grace gave her 6. Before that, Paul gave her 4. By working backward from 13, and subtracting six and then 4, we end up with 3, the number of marbles Meghan started with.