Donald Trump on the day New Hampshire voters head to the polls in the primary election estimated for the first time that his infamous wall on the southern border would cost $8 billion — and insisted yet again that Mexico will pay for it.

Asked how Trump came up with that number by MSNBC host Tamron Hall, the GOP front-runner explained that it is a “very simple calculation.”

“What we’re doing is we have 2,000 miles, right? 2,000 miles. It’s long but not 13,000 miles like they have in China,” he said, comparing his self-declared great wall with the Great Wall of China, which took hundreds of years to build and reportedly resulted in the death of hundreds of thousands of workers. “Of the 2,000, we don’t need 2,000, we need 1,000 because we have natural barriers … and I’m taking it price per square foot and a price per square, you know, per mile,” he said.

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The candidate added that his wall will probably be 35 to 40 feet high — a “real wall” he said. And that it will be one that “actually looks good, you know, as good as a wall is going to look.”

Trump declared last fall that if elected president of the United States, he would build a wall along the Mexican border — and that the country would shell out to make it happen for him.

“I would build a great wall, and nobody builds walls better than me, believe me, and I’ll build them very inexpensively. I will build a great, great wall on our southern border. And I will have Mexico pay for that wall,” Trump said in his presidential announcement speech. ”Mark my words.”

CNBC reported that if Trump were to build this wall, the cost would be in the billions (more like 15-25) – and that doesn’t account for other expenses, including associated infrastructure and yearly maintenance.

Hall noted that just yesterday, the former president of Mexico called Trump’s idea for a wall “stupid,” adding that “we are not going to pay any single cent.” Probing how he plans to get Mexico to pay for his wall, Trump responded, “Mexico makes a fortune. Mexico is going to pay. And I heard he said that we will not pay. Guess what? The wall just got higher.”