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Metamath Proof Explorer

Theorem nn0ssq

Description: The nonnegative integers are a subset of the rationals. (Contributed by NM, 31-Jul-2004)

Ref Expression
Assertion nn0ssq 
|- NN0 C_ QQ

Proof

Step Hyp Ref Expression
1 nn0ssz 
 |-  NN0 C_ ZZ
2 zssq 
 |-  ZZ C_ QQ
3 1 2 sstri 
 |-  NN0 C_ QQ