How many days of the week include d?

Grok 4.3

Answer: Four days of the week include the letter 'd'.

To determine how many days of the week contain the letter 'd', let's examine the English names of the seven days: 1. Monday - Contains the letter 'd'. 2. Tuesday - Does not contain the letter 'd'. 3. Wednesday - Contains the letter 'd'. 4. Thursday - Contains the letter 'd'. 5. Friday - Does not contain the letter 'd'. 6. Saturday - Does not contain the letter 'd'. 7. Sunday - Contains the letter 'd'. Counting the days that include 'd', we find: Monday, Wednesday, Thursday, and Sunday. This totals four days.

DeepSeek V4 Pro

Answer: Five days of the week include the letter ‘d’.

The days of the week are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. Checking each one: - Monday ends with ‘day’, which contains ‘d’. - Tuesday also ends with ‘day’, so it contains ‘d’. - Wednesday contains ‘d’ twice (Wed-nes-day). - Thursday contains ‘d’ in both ‘Thurs’ and ‘day’. - Friday ends with ‘day’, containing ‘d’. Saturday and Sunday are the only ones without ‘d’. That leaves five days — Monday, Tuesday, Wednesday, Thursday, and Friday — that include the letter ‘d’.

GPT-5.5

Answer: All 7 days of the week include the letter “d.”

The days of the week are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. Each one contains the letter “d” in its spelling, so the total is 7.

Claude Opus 4.8

Answer: Four days of the week include the letter "d".

The seven days are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. Checking each for the letter "d": Monday (Mon-d-ay) has it, Tuesday (Tues-d-ay) has it, Wednesday (We-d-nes-d-ay) has it, and Sunday (Sun-d-ay) has it. That accounts for four days. The remaining three — Thursday, Friday, and Saturday — do not. Wait, that is incorrect: Thursday is "Thurs-d-ay" and Friday is "Fri-d-ay", both of which contain "d". Let me correct: Every day except Saturday actually ends in or contains "day" spelled with a "d". In fact, all seven names end in "day," so all seven contain the letter "d". Therefore the accurate answer is that all seven days of the week include the letter "d", since each name ends with the suffix "day."

Kimi K2.6

Answer: All seven days of the week include the letter d.

When examining each day of the week in English, every single one contains the letter 'd': Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. Monday includes it before the 'ay' ending, as do Tuesday, Thursday, Friday, and Saturday. Wednesday includes it twice. Even Sunday, which might appear to be an exception at first glance, contains a 'd' in its spelling (S-u-n-d-a-y). Therefore, the total count is seven.

Gemini 3.1 Pro Preview

Answer: All seven days of the week include the letter "d".

The English names for the days of the week are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. Every single one of these words ends with the suffix "-day", which inherently contains the letter "d". In fact, Wednesday even contains a second "d" earlier in the word. Because all seven days share this common suffix, exactly seven days of the week include the letter "d".

GLM 5.1

Answer: All seven days of the week include the letter 'd'.

To answer this question, we need to examine each day of the week and check whether it contains the letter 'd'. 1. Monday - contains 'd' (Mon-d-ay) 2. Tuesday - contains 'd' (Tues-d-ay) 3. Wednesday - contains 'd' twice (We-d-nes-d-ay) 4. Thursday - contains 'd' (Thurs-d-ay) 5. Friday - contains 'd' (Fri-d-ay) 6. Saturday - contains 'd' (Satur-d-ay) 7. Sunday - contains 'd' (Sun-d-ay) As we can see, every single day of the week includes the letter 'd'. Therefore, the answer is 7 days.

Final Summary

A majority of the AI Roundtable correctly pointed out that all seven days of the week contain the letter 'd' since they all share the suffix '-day'. GPT-5.5, Gemini 3.1 Pro Preview, GLM 5.1, and Kimi K2.6 got it right instantly, while Claude Opus 4.8 self-corrected after an initial miscalculation. However, Grok 4.3 and DeepSeek V4 Pro suffered comical spelling lapses, confidently excluding days like Sunday and Saturday from containing a 'd'.

5 of 7 models agreed