Letter Equation Riddles

I¹ wrote this series of puzzles in university. I'd definitely seen the format somewhere before, but it was only upon getting some friends to review these puzzles while preparing it for my website that I discovered they're called Ditloids.

These riddles involve identifying an original phrase whose words have largely been replaced with their first letter. For example, 3 B Ms (S H T R) may be 3 Blind Mice (See How They Run). Plurals should be marked with an 's' even if absent from their plural form, as with Ms and Mice.

0 D 30
1 R to R T A
2 Ps in a P
3 Hs on a C (with a S H)
4 Fs on 1 H (E Y T)
5 Es: E, A, F, W and A
6 G a-L (in the 12 Ds of C)
7 Cs of the R
8 Ss on a S S
9 Ls (but O I Y are a C)
10, X in R Ns
11, the A N of S (Na)
12 M Ns (A, A-S, B, C, C-S, D, D-S, E, F, F-S, G, G-S)
13 is Y A at the E of Y F Y of HS
14 Es of F (before it was C)
15 Ms in a Q of an H
16 Ps in a C S
17 Ss in a G (and 29 Ks in a S)
18, the G of the N Gs (on the P T)
I W O 19 (a S about the V W)
20 Ss on a D B
21, the L D A (in the U S)
28 Ds in F, B...
29 Ds in F in a L Y
40 Rs to S in this P
42, the A to the Q of L, the U and E
54 Ss on a R's C
69 L L C (the S of the Z), when V S
100 Ds C (the T at W W Bs)
195 Cs (I the H S and the S of P)
300 S (at the B of T)
896 T P in R & B, G & S, R & S, D & P, B & W, X & Y, S & M and S & S.
1789, the B of the F R
2033, the PC of K
20000 Ls U the S
525600 Ms (H D Y M? M a Y?)
1000000 Ds, the A of M D by D. E
8675309/J (by T T)
299792458 Ms/S, the S of L
01189998819991197253, an E N that's E to R (from the IT C)\