Best practice RSpec example formatting for a multiple "simple" expectations - testing

Question

I'm tryna improve my RSpec skills following the bests practices.
I have a simple method is_multiple_of_3_or_5? and I'm implementing a test for it using simple testing values. My first approach was:
describe '#is_multiple_of_3_or_5?' do
context "when input is multiple of 3 or 5" do
expect(is_multiple_of_3_or_5?(3)).to be true
expect(is_multiple_of_3_or_5?(5)).to be true
expect(is_multiple_of_3_or_5?(51)).to be true
expect(is_multiple_of_3_or_5?(45)).to be true
end
end
I like it because it's very short and the test cases are simple, so no need to complicate it.. But I've read in the RSpec style guide that it should be only one expectation per example.
So I refactored in 2 other ways:
One it per example:
describe '#is_multiple_of_3_or_5?' do
context 'when input is multiple of 3 or 5' do
it "is true for 3" do
expect(is_multiple_of_3_or_5?(3)).to be true
end
it "is true for 5" do
expect(is_multiple_of_3_or_5?(5)).to be true
end
it "is true for 51" do
expect(is_multiple_of_3_or_5?(51)).to be true
end
it "is true for 45" do
expect(is_multiple_of_3_or_5?(45)).to be true
end
end
end
Drying up with a subject block
describe '#is_multiple_of_3_or_5?' do
context 'when input is multiple of 3 or 5' do
subject { is_multiple_of_3_or_5?(input) }
context 'when input is 3' do
let(:input) { 3 }
it { is_expected.to be true }
end
context 'when input is 5' do
let(:input) { 5 }
it { is_expected.to be true }
end
context 'when input is 51' do
let(:input) { 51 }
it { is_expected.to be true }
end
context 'when input is 45' do
let(:input) { 45 }
it { is_expected.to be true }
end
end
end
So I have 2 questions:
In the case of theses 2 last versions, the test became really bigger, is it really worth it? Considering that the values tested are simple integers?
Which one of these 2 versions are better formatted?
Thank you for anyone who could help me take better perspective on RSpec!