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" .
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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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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 |
|---|---|---|---|---|---|---|
| 449 | 398 | 1 | 51 | 0 | 1 | -1 |
| 398 | 51 | 7 | 41 | 1 | -1 | 8 |
| 51 | 41 | 1 | 10 | -1 | 8 | -9 |
| 41 | 10 | 4 | 1 | 8 | -9 | 44 |
| 10 | 1 | 10 | 0 | -9 | 44 | -449 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 923 | 93 | 9 | 86 | 0 | 1 | -9 |
| 93 | 86 | 1 | 7 | 1 | -9 | 10 |
| 86 | 7 | 12 | 2 | -9 | 10 | -129 |
| 7 | 2 | 3 | 1 | 10 | -129 | 397 |
| 2 | 1 | 2 | 0 | -129 | 397 | -923 |
Source: ExtendedEuclideanAlgorithm.com
| n | b | q | r | t1 | t2 | t3 |
|---|---|---|---|---|---|---|
| 193 | 952 | 0 | 193 | 0 | 1 | 0 |
| 952 | 193 | 4 | 180 | 1 | 0 | 1 |
| 193 | 180 | 1 | 13 | 0 | 1 | -1 |
| 180 | 13 | 13 | 11 | 1 | -1 | 14 |
| 13 | 11 | 1 | 2 | -1 | 14 | -15 |
| 11 | 2 | 5 | 1 | 14 | -15 | 89 |
| 2 | 1 | 2 | 0 | -15 | 89 | -193 |
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 ≡ 962 × 398-1 (mod 449) ≡ 962 × 44 (mod 449) ≡ 122 (mod 449)x ≡ 419 × 93-1 (mod 923) ≡ 419 × 397 (mod 923) ≡ 203 (mod 923)x ≡ 406 × 952-1 (mod 193) ≡ 406 × 89 (mod 193) ≡ 43 (mod 193)
So now we have the following equations of the form x ≡ a (mod m):
x ≡ 122 (mod 449)
x ≡ 203 (mod 923)
x ≡ 43 (mod 193)
Now the actual calculation
- Find the common modulus M
M = m1 × m2 × ... × mk = 449 × 923 × 193 = 79984411 - We calculate the numbers M1 to M3
M1=M/m1=79984411/449=178139,M2=M/m2=79984411/923=86657,M3=M/m3=79984411/193=414427 - 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 -193 mod 449 ≡ 256n b q r t1 t2 t3 449 178139 0 449 0 1 0 178139 449 396 335 1 0 1 449 335 1 114 0 1 -1 335 114 2 107 1 -1 3 114 107 1 7 -1 3 -4 107 7 15 2 3 -4 63 7 2 3 1 -4 63 -193 2 1 2 0 63 -193 449
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -378 mod 923 ≡ 545n b q r t1 t2 t3 923 86657 0 923 0 1 0 86657 923 93 818 1 0 1 923 818 1 105 0 1 -1 818 105 7 83 1 -1 8 105 83 1 22 -1 8 -9 83 22 3 17 8 -9 35 22 17 1 5 -9 35 -44 17 5 3 2 35 -44 167 5 2 2 1 -44 167 -378 2 1 2 0 167 -378 923
Source: ExtendedEuclideanAlgorithm.com
So our multiplicative inverse is -31 mod 193 ≡ 162n b q r t1 t2 t3 193 414427 0 193 0 1 0 414427 193 2147 56 1 0 1 193 56 3 25 0 1 -3 56 25 2 6 1 -3 7 25 6 4 1 -3 7 -31 6 1 6 0 7 -31 193
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
= (122 × 178139 × 256 +
203 × 86657 × 545 +
43 × 414427 × 162) mod 79984411
= 41340450 (mod 79984411)
So our answer is 41340450 (mod 79984411).
Verification
So we found that x ≡ 41340450
If this is correct, then the following statements (i.e. the original equations) are true:
398x (mod 449) ≡ 962 (mod 449)
93x (mod 923) ≡ 419 (mod 923)
952x (mod 193) ≡ 406 (mod 193)
Let's see whether that's indeed the case if we use x ≡ 41340450.