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 |
|---|---|---|---|---|---|---|
| 767 | 223 | 3 | 98 | 0 | 1 | -3 |
| 223 | 98 | 2 | 27 | 1 | -3 | 7 |
| 98 | 27 | 3 | 17 | -3 | 7 | -24 |
| 27 | 17 | 1 | 10 | 7 | -24 | 31 |
| 17 | 10 | 1 | 7 | -24 | 31 | -55 |
| 10 | 7 | 1 | 3 | 31 | -55 | 86 |
| 7 | 3 | 2 | 1 | -55 | 86 | -227 |
| 3 | 1 | 3 | 0 | 86 | -227 | 767 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 439 | 216 | 2 | 7 | 0 | 1 | -2 |
| 216 | 7 | 30 | 6 | 1 | -2 | 61 |
| 7 | 6 | 1 | 1 | -2 | 61 | -63 |
| 6 | 1 | 6 | 0 | 61 | -63 | 439 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 218 | 415 | 0 | 218 | 0 | 1 | 0 |
| 415 | 218 | 1 | 197 | 1 | 0 | 1 |
| 218 | 197 | 1 | 21 | 0 | 1 | -1 |
| 197 | 21 | 9 | 8 | 1 | -1 | 10 |
| 21 | 8 | 2 | 5 | -1 | 10 | -21 |
| 8 | 5 | 1 | 3 | 10 | -21 | 31 |
| 5 | 3 | 1 | 2 | -21 | 31 | -52 |
| 3 | 2 | 1 | 1 | 31 | -52 | 83 |
| 2 | 1 | 2 | 0 | -52 | 83 | -218 |
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 ≡ 672 × 223-1 (mod 767) ≡ 672 × 540 (mod 767) ≡ 89 (mod 767)x ≡ 791 × 216-1 (mod 439) ≡ 791 × 376 (mod 439) ≡ 213 (mod 439)x ≡ 335 × 415-1 (mod 218) ≡ 335 × 83 (mod 218) ≡ 119 (mod 218)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 89 (mod 767)
x ≡ 213 (mod 439)
x ≡ 119 (mod 218)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 767 × 439 × 218 = 73403434 - We calculate the numbers M1 to M3
M1=M/m1=73403434/767=95702,M2=M/m2=73403434/439=167206,M3=M/m3=73403434/218=336713 - 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 133 mod 767 ≡ 133n b q r t1 t2 t3 767 95702 0 767 0 1 0 95702 767 124 594 1 0 1 767 594 1 173 0 1 -1 594 173 3 75 1 -1 4 173 75 2 23 -1 4 -9 75 23 3 6 4 -9 31 23 6 3 5 -9 31 -102 6 5 1 1 31 -102 133 5 1 5 0 -102 133 -767
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -58 mod 439 ≡ 381n b q r t1 t2 t3 439 167206 0 439 0 1 0 167206 439 380 386 1 0 1 439 386 1 53 0 1 -1 386 53 7 15 1 -1 8 53 15 3 8 -1 8 -25 15 8 1 7 8 -25 33 8 7 1 1 -25 33 -58 7 1 7 0 33 -58 439
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -9 mod 218 ≡ 209n b q r t1 t2 t3 218 336713 0 218 0 1 0 336713 218 1544 121 1 0 1 218 121 1 97 0 1 -1 121 97 1 24 1 -1 2 97 24 4 1 -1 2 -9 24 1 24 0 2 -9 218
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
= (89 × 95702 × 133 +
213 × 167206 × 381 +
119 × 336713 × 209) mod 73403434
= 27803839 (mod 73403434)
So our answer is 27803839 (mod 73403434).
Verification
So we found that x ≡ 27803839
If this is correct, then the following statements (i.e. the original equations) are true:
223x (mod 767) ≡ 672 (mod 767)
216x (mod 439) ≡ 791 (mod 439)
415x (mod 218) ≡ 335 (mod 218)
Let's see whether that's indeed the case if we use x ≡ 27803839.