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.
This fills all textboxes with random numbers. If you fill in random numbers yourself, it is very likely that those numbers do not have a solution. To avoid disappointment, use this button instead! It only uses random numbers that do have a solution.
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 |
|---|---|---|---|---|---|---|
| 383 | 985 | 0 | 383 | 0 | 1 | 0 |
| 985 | 383 | 2 | 219 | 1 | 0 | 1 |
| 383 | 219 | 1 | 164 | 0 | 1 | -1 |
| 219 | 164 | 1 | 55 | 1 | -1 | 2 |
| 164 | 55 | 2 | 54 | -1 | 2 | -5 |
| 55 | 54 | 1 | 1 | 2 | -5 | 7 |
| 54 | 1 | 54 | 0 | -5 | 7 | -383 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 449 | 646 | 0 | 449 | 0 | 1 | 0 |
| 646 | 449 | 1 | 197 | 1 | 0 | 1 |
| 449 | 197 | 2 | 55 | 0 | 1 | -2 |
| 197 | 55 | 3 | 32 | 1 | -2 | 7 |
| 55 | 32 | 1 | 23 | -2 | 7 | -9 |
| 32 | 23 | 1 | 9 | 7 | -9 | 16 |
| 23 | 9 | 2 | 5 | -9 | 16 | -41 |
| 9 | 5 | 1 | 4 | 16 | -41 | 57 |
| 5 | 4 | 1 | 1 | -41 | 57 | -98 |
| 4 | 1 | 4 | 0 | 57 | -98 | 449 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 847 | 234 | 3 | 145 | 0 | 1 | -3 |
| 234 | 145 | 1 | 89 | 1 | -3 | 4 |
| 145 | 89 | 1 | 56 | -3 | 4 | -7 |
| 89 | 56 | 1 | 33 | 4 | -7 | 11 |
| 56 | 33 | 1 | 23 | -7 | 11 | -18 |
| 33 | 23 | 1 | 10 | 11 | -18 | 29 |
| 23 | 10 | 2 | 3 | -18 | 29 | -76 |
| 10 | 3 | 3 | 1 | 29 | -76 | 257 |
| 3 | 1 | 3 | 0 | -76 | 257 | -847 |
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 ≡ 404 × 985-1 (mod 383) ≡ 404 × 7 (mod 383) ≡ 147 (mod 383)x ≡ 697 × 646-1 (mod 449) ≡ 697 × 351 (mod 449) ≡ 391 (mod 449)x ≡ 698 × 234-1 (mod 847) ≡ 698 × 257 (mod 847) ≡ 669 (mod 847)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 147 (mod 383)
x ≡ 391 (mod 449)
x ≡ 669 (mod 847)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 383 × 449 × 847 = 145656049 - We calculate the numbers M1 to M3
M1=M/m1=145656049/383=380303,M2=M/m2=145656049/449=324401,M3=M/m3=145656049/847=171967 - 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 -24 mod 383 ≡ 359n b q r t1 t2 t3 383 380303 0 383 0 1 0 380303 383 992 367 1 0 1 383 367 1 16 0 1 -1 367 16 22 15 1 -1 23 16 15 1 1 -1 23 -24 15 1 15 0 23 -24 383
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is 149 mod 449 ≡ 149n b q r t1 t2 t3 449 324401 0 449 0 1 0 324401 449 722 223 1 0 1 449 223 2 3 0 1 -2 223 3 74 1 1 -2 149 3 1 3 0 -2 149 -449
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -228 mod 847 ≡ 619n b q r t1 t2 t3 847 171967 0 847 0 1 0 171967 847 203 26 1 0 1 847 26 32 15 0 1 -32 26 15 1 11 1 -32 33 15 11 1 4 -32 33 -65 11 4 2 3 33 -65 163 4 3 1 1 -65 163 -228 3 1 3 0 163 -228 847
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
= (147 × 380303 × 359 +
391 × 324401 × 149 +
669 × 171967 × 619) mod 145656049
= 66461371 (mod 145656049)
So our answer is 66461371 (mod 145656049).
Verification
So we found that x ≡ 66461371
If this is correct, then the following statements (i.e. the original equations) are true:
985x (mod 383) ≡ 404 (mod 383)
646x (mod 449) ≡ 697 (mod 449)
234x (mod 847) ≡ 698 (mod 847)
Let's see whether that's indeed the case if we use x ≡ 66461371.