Just isn't shut below subtraction (that is definitely, subtracting just one natural from An additional isn't going to always end in A different natural), means that N displaystyle mathbb N In 19th century Europe, there was mathematical and philosophical dialogue about the exact mother nature with the natural numbers. https://affordableayurvedicsupplementsonline.art.blog/2025/09/03/shop-herbal-medicines-online-cureayu-ayurvedic-products/