Welcome to ChineseRemainderTheorem.com!
Use the calculator below to get a step-by-step calculation of the Chinese Remainder Theory. Just enter the numbers you would like and press "Calculate" .
This removes all numbers from the textboxes, such that you can fill in your own.
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This button is similar to the "Clear everything" button, but only clears the left column.
This is useful if you want your equations to be of the form x ≡ a (mod m) rather than bx ≡ a (mod m).
In that case, it can be especially useful after using the random numbers button.
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Are you ready to view a full step-by-step Chinese Remainder Theorem calculation for the numbers you have entered? Then use this button!
Want to know more?- Read about how to execute the Chinese Remainder Theorem
- Discover different ways to calculate multiplicative inverses
Transform the equations
You used one or more of the fields on the left, so your equations are of the form bx ≡ a mod m.
We want them to be of the form x ≡ a mod m, so we need to move the values on the left to the right side of the equation.
For a more detailed explanation about how this works, see this part of our page about how to execute the Chinese Remainder algorithm.
First, we calculate the inverses of the leftmost value on each row:
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 601 | 242 | 2 | 117 | 0 | 1 | -2 |
| 242 | 117 | 2 | 8 | 1 | -2 | 5 |
| 117 | 8 | 14 | 5 | -2 | 5 | -72 |
| 8 | 5 | 1 | 3 | 5 | -72 | 77 |
| 5 | 3 | 1 | 2 | -72 | 77 | -149 |
| 3 | 2 | 1 | 1 | 77 | -149 | 226 |
| 2 | 1 | 2 | 0 | -149 | 226 | -601 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 956 | 497 | 1 | 459 | 0 | 1 | -1 |
| 497 | 459 | 1 | 38 | 1 | -1 | 2 |
| 459 | 38 | 12 | 3 | -1 | 2 | -25 |
| 38 | 3 | 12 | 2 | 2 | -25 | 302 |
| 3 | 2 | 1 | 1 | -25 | 302 | -327 |
| 2 | 1 | 2 | 0 | 302 | -327 | 956 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 837 | 485 | 1 | 352 | 0 | 1 | -1 |
| 485 | 352 | 1 | 133 | 1 | -1 | 2 |
| 352 | 133 | 2 | 86 | -1 | 2 | -5 |
| 133 | 86 | 1 | 47 | 2 | -5 | 7 |
| 86 | 47 | 1 | 39 | -5 | 7 | -12 |
| 47 | 39 | 1 | 8 | 7 | -12 | 19 |
| 39 | 8 | 4 | 7 | -12 | 19 | -88 |
| 8 | 7 | 1 | 1 | 19 | -88 | 107 |
| 7 | 1 | 7 | 0 | -88 | 107 | -837 |
Source: ExtendedEuclideanAlgorithm.com
Click on any row to reveal a more detailed calculation of each multiplicative inverse.
Now that we now the inverses, let's move the leftmost value on each row to the right of the equation:
x ≡ 307 × 242-1 (mod 601) ≡ 307 × 226 (mod 601) ≡ 267 (mod 601)x ≡ 28 × 497-1 (mod 956) ≡ 28 × 629 (mod 956) ≡ 404 (mod 956)x ≡ 209 × 485-1 (mod 837) ≡ 209 × 107 (mod 837) ≡ 601 (mod 837)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 267 (mod 601)
x ≡ 404 (mod 956)
x ≡ 601 (mod 837)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 601 × 956 × 837 = 480903372 - We calculate the numbers M1 to M3
M1=M/m1=480903372/601=800172,M2=M/m2=480903372/956=503037,M3=M/m3=480903372/837=574556 - We now calculate the modular multiplicative inverses M1-1 to M3-1
Have a look at the page that explains how to calculate modular multiplicative inverse.
Using, for example, the Extended Euclidean Algorithm, we will find that:
So our multiplicative inverse is 202 mod 601 ≡ 202n b q r t1 t2 t3 601 800172 0 601 0 1 0 800172 601 1331 241 1 0 1 601 241 2 119 0 1 -2 241 119 2 3 1 -2 5 119 3 39 2 -2 5 -197 3 2 1 1 5 -197 202 2 1 2 0 -197 202 -601
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -375 mod 956 ≡ 581n b q r t1 t2 t3 956 503037 0 956 0 1 0 503037 956 526 181 1 0 1 956 181 5 51 0 1 -5 181 51 3 28 1 -5 16 51 28 1 23 -5 16 -21 28 23 1 5 16 -21 37 23 5 4 3 -21 37 -169 5 3 1 2 37 -169 206 3 2 1 1 -169 206 -375 2 1 2 0 206 -375 956
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is 47 mod 837 ≡ 47n b q r t1 t2 t3 837 574556 0 837 0 1 0 574556 837 686 374 1 0 1 837 374 2 89 0 1 -2 374 89 4 18 1 -2 9 89 18 4 17 -2 9 -38 18 17 1 1 9 -38 47 17 1 17 0 -38 47 -837
Source: ExtendedEuclideanAlgorithm.com
- Now we can calculate x with the equation we saw earlier
x = (a1 × M1 × M1-1 + a2 × M2 × M2-1 + ... + ak × Mk × Mk-1) mod M
= (267 × 800172 × 202 +
404 × 503037 × 581 +
601 × 574556 × 47) mod 480903372
= 7472500 (mod 480903372)
So our answer is 7472500 (mod 480903372).
Verification
So we found that x ≡ 7472500
If this is correct, then the following statements (i.e. the original equations) are true:
242x (mod 601) ≡ 307 (mod 601)
497x (mod 956) ≡ 28 (mod 956)
485x (mod 837) ≡ 209 (mod 837)
Let's see whether that's indeed the case if we use x ≡ 7472500.