Let us calculate the speed of light from permittivity of free space and permeability of free space.

ε0 = 8.8541878188(14)×10−12 F⋅m−1

μ0 = 1.25663706127(20)×10−6 N⋅A−2

10     REM CALCULATE SPEED OF LIGHT
20    MUZERO=1.2566370612720E-6
30    EPZERO=8.854187818814E-12
60    C=1/SQR(MUZERO*EPZERO)
70     PRINT " SPEED OF LIGHT c = ",C,"m/s"
80     END

Or we can simply write directly as

10     REM CALCULATE SPEED OF LIGHT
20    C=1/SQR(1.2566371E-6*8.8541878E-12)
30     PRINT " SPEED OF LIGHT  c = ",C,"m/s"
40     END

READY
>RUN

 SPEED OF LIGHT  c =  2.9979245 E+8 m/s

READY
>

10     REM CALCULATE SPEED OF LIGHT
20    MUZERO=1.2566370612720E-6
30    EPZERO=8.854187818814E-12
40    rem X=MUZERO*EPZERO
50    rem Y=SQR(X)
60    C=1/SQR(muzero*epzero)
70     PRINT " SPEED OF LIGHT = ",C, "m/s"
80     END
90 rem MUZERO = 1.2566370612720e-6
100 rem EPZERO = 8.854187818814e-12
110 rem MUZERO * EPZERO = 1.1126500560584764552371408e-17
120 rem SQR(MUZERO * EPZERO) = 3.3356409519888024891312226903836e-9
130 rem C = 29,97,92,457.99934552707422964167902

 The above is comparison data between BASIC-52 and MS Windows calculator results.

10     REM CALCULATE SPEED OF LIGHT
20    MUZERO=PI*4E-7
30    EPZERO=8.854187818814E-12
60    C=1/SQR(MUZERO*EPZERO)
70     PRINT " SPEED OF LIGHT = ",C,"m/s"
80     END

The above uses constant PI directly and gives only 2m error.

READY
>RUN

 SPEED OF LIGHT =  2.9979246 E+8 m/s